#define SCARD_ATTR_CHARACTERISTICS SCARD_ATTR_VALUE(SCARD_CLASS_MECHANICAL, 0x0150) /**< DWORD indicating which mechanical characteristics are supported. If zero, no special characteristics are supported. Note that multiple bits can be set */

#define SCARD_ATTR_DEVICE_UNIT SCARD_ATTR_VALUE(SCARD_CLASS_SYSTEM, 0x0001) /**< Instance of this vendor's reader attached to the computer. The first instance will be device unit 0, the next will be unit 1 (if it is the same brand of reader) and so on. Two different brands of readers will both have zero for this value. */